International Journal of Engineering Research & Technology (IJERT) ISSN: 2278-0181 Vol. 3 Issue 5, May - 2014 Kinetic Modelling for Coal Liquefaction Process Rohitbabu .G. Nalwala[1]; Pravat Kumar Rana[2]; Deepak H. Shukla[3] Chemical Engineering Department, Gharda Institute of Technology, At/Po-Lavel, Tal-Khed, Dist.-Ratnagiri, Maharashtra (India) Abstract- In 1913 Bergius developed the coal hydro the principal products can be high molecular mass fuels, liquefaction. In 1917 there were clear indication of decline in distillate fuel Oils, gasoline, or chemical feedstocks. domestic oil production and possibility of international shortage The products of both indirect and direct liquefaction have was realized. Around to be 1970 the chevron started coal higher energy content than coal. Coal typically contains 60 liquefaction process. He had designed and executed the wt% of the heating value of the liquefied products. The production of synthetic fuel, but had not given any kinetic model for monitoring the reaction. Our main focus is on to development liquids produced by the two methods are very different in a kinetic model of reaction taking place and estimating the chemical composition. Synthesis gas conversion processes kinetic parameter like rate constant, order of the reaction using give saturated hydrocarbon liquids, whereas the products of optimization technique like regression, PSO (Particle Swamp direct liquefaction are highly aromatic. These chemical Optimization) validating it with experimental values. The differences affect the end use. Indirect liquefaction provides validating incorporate kinetic rate constant, conversion to cross high-quality diesel fuel and intermediates for olefin verify the result obtained through optimization. production; direct liquefaction yields high-octane gasoline and Scope of this work is to get a better insight of coal excellent feedstocks for aromatic chemicals. liquefaction process to operate it under optimal condition. In Direct and indirect liquefaction have both been used addition to this it can gives us the various rate determining steps, so as it can be applied to variety of the coals available in the commercially to produce liquids from used commercially to world. produce liquids from coal. The first developments took place th in Germany during the 19 century. Berthelot discovered that coal can be converted to oil by chemical reduction. Bergius Keywords- Liquefaction, Direct liquefaction, indirect (1911) demonstrated the noncatalytic conversion of coal to liquefaction, Kinetic behavior, PSO. heavy crude oil by using a solvent and hydrogen pressure. IJERTChevron Research Co. began research that led to development I. INTRODUCTION IJERTof a two-stage process, first publicly reported in 1982; thermal Coal liquefaction is a term which is used to describe a liquefaction in the first stage was followed by catalytic process in which a portion of the organic coal substance is hydroprocessing in the second; direct feed of effluent from the converted to liquid products. In general, this includes liquids first to the second reactor was claimed to minimize extracted by solvents. Solvent extraction has also been used condensation of thermal products; it was scaled to 6 tons/day1. extensively in research on coal structure. More specifically, coal liquefaction involves producing liquids by chemically Above mention author have carried out the practical altering the coal structure and increasing the content of execution the coal liquefaction and they have shown effort of hydrogen relative to carbon. At the same time, nitrogen, various variables on conversion yield and quality of liquid sulfur, oxygen, and mineral matter are removed. Compared hydrocarbons obtained. Berthelot has design a two stage with other fuels, coal is particularly low in hydrogen. The process to increase the yield of liquid products and shown the hydrogen consumed in producing liquids of increased effect of composition on hydrogen consumption and product hydrogen content and in removing heteroatoms represents a specification. large part of the cost of coal liquefaction. Liquefaction Above mentioned authors have not shown the kinetic study methods can be classified as indirect liquefaction and direct order of the reaction, kinetic rate constant determination. So liquefaction. we carried out this work to carryout kinetic studies and for the In indirect liquefaction, coal reacts with oxygen and rate parameter estimation. Here we are using particle swarm steam at high temperature to produce a mixture of carbon optimization (PSO). monoxide and hydrogen (synthesis gas), which can be catalytically converted to liquid products. The best-known II. LITERATURE SURVEY process, the Fischer–Tropsch synthesis, produces a mixture of gaseous, liquid, and solid hydrocarbons. BERGIUS PROCESS: In direct liquefaction, coal reacts at elevated temperature The coal is finely ground and dried in a stream of hot gas. and pressure with gaseous hydrogen and a solvent that is a The dry product is mixed with heavy oil recycled from the hydrogen-donor. Conversion to liquids can be realized with or process. Catalyst is typically added to the mixture. A number without added catalysts. According to the conditions chosen, of catalysts have been developed over the years, including IJERTV3IS051422 www.ijert.org 1205 International Journal of Engineering Research & Technology (IJERT) ISSN: 2278-0181 Vol. 3 Issue 5, May - 2014 tungsten or molybdenum sulfides, tin or nickel oleate, and pressures. A second reaction was a hydrogenation others. Alternatively, iron sulphides present in the coal may /hydrocracking reaction needed to generate recycle oil and have sufficient catalytic activity for the process, which was product oil. This second reaction appeared to be the most the original Bergius process. There are also considerations suitable for catalytic control. However, as the conditions with respect to global warming, especially if coal liquefaction necessary for the dissolution reaction are not necessarily is conducted without carbon capture and storage technologies. optimal for recycle oil generation, the concept was developed The mixture is pumped into a reactor. The reaction occurs at of separating, but closely coupling, the dissolution step and between 400 to 500 °C and 20 to 70 MPa hydrogen pressure. the hydrogenation /hydrocracking step. This original concept The reaction produces heavy oils, middle oils, gasoline, and has evolved into the current generation of CCLP, shown in gases. The overall reaction can be summarized as follows: figure below [1]. nC (n x 1)H2 CnH2n2x2 (1) Chevron two stage concept for coal liquefaction: (where x = Degrees of Unsaturation) The immediate product from the reactor must be stabilized by passing it over a conventional hydrotreating catalyst. The product stream is high in naphthenes and aromatics, low in paraffin’s and very low in olefins. The different fractions can be passed to further processing (cracking, reforming) to output synthetic fuel of desirable quality. If passed through a process such as Plat forming, most of the naphthenes are converted to aromatics and the recovered hydrogen recycled to the process. The liquid product from Plat forming will contain over 75% aromatics and has a Research Octane Number of over 105. Overall, about 97% of input carbon fed directly to the process can be converted into synthetic fuel. However, any carbon used in generating hydrogen will be lost as carbon dioxide, so reducing the overall carbon efficiency of the process. [1] There is a residue of unreactive tarry compounds mixed Fig 1 - Block diagram of chevron two stage process with ash from the coal and catalyst. To minimize the loss of carbon in the residue stream, it is necessary to have a low-ash CCLP uses a two-stage approach to liquefaction by using feed. Typically the coal should be <10% ash by weight. The two separate, but close-coupled, reaction zones. Slurry hydrogen required for the process can be also produced fromIJERTIJERT prepared from process-derived recycle oil is fed to the first- coal or the residue by steam reforming. A typical hydrogen stage reactor, and effluent from this first reactor can be fed demand is ~8 kg hydrogen per ton of dry, ash-free coal. directly to the second-stage reactor containing a coal Generally, this process is similar to hydrogenation. The output hydroprocessing catalyst. The function of the first stage is to is at three levels: heavy oil, middle oil, gasoline. The middle solubilize the coal, whereas the function of the second is to stabilize the first-stage effluent and upgrade it to acceptable oil is hydrogenated in order to get more gasoline and the [1] heavy oil is mixed with the coal again and the process restarts. product and recycle oils . In this way, heavy oil and middle oil fractions are also reused in this process. Product distribution for coal liquefied using CCLP: THE CHEVRON COAL LIQUEFACTION PROCESS: Feed coal Product Sub- Australian Chevron Research initiated a number of new studies on (wt %) bituminous brown coal synthetic fuels with emphasis on ‘second generation’ process coal options. The Middle East oil embargo of 1973- 1974 was a C1-C3 10.7 10.2 powerful stimulant for this work, as were subsequent events in >C4 liquid 65.2 66.1 Iran and Iraq. Although the current world oil situation is less Undissolved coal 11.8 4.5 volatile, and some concerns have eased, it is nonetheless still H2O,COx,H2S,NH3 20.0 28.0 true that sudden changes may occur with little warning. For